After all that running around for other people, it must be nice to do your own jobs for a change, eh? Tommy's missions are some of the best missions in the game - sometimes tricky or needing though, sometimes bloodbaths.
After you head to the Kent Paul contact point, opened after your "Sir! Yes Sir" mission for Cortez, the annoying Mockney tells you that Lance, who clearly suffers from Premature Eradication, has tried to off Diaz - in vengeance for his brother's death - and missed. Diaz has him held at the Junkyard.
First off, you've got to race to the junkyard - and I mean RACE. Lance is being tortured to death, and you've got to get there before it happens. A lot of people favour using a helicopter (now west Vice City is opened, you've got easy access to two, or three with 80 packages collected or four with Hyman Condo bought), but that would require you taking one to the Malibu, so it's ready for you to jump in. Almost ANY car will get you there in time to fight through the Junk Yard and get to Lance so don't panic too much - the slower you go, the more efficient you'll need to be when you get there. The Junk Yard is opposite the Little Haiti pizza parlour - so I tend to head across Starfish Island to get there, for reference.
The junkyard is heavily populated with goons carrying Rugers and MP5s. These all hurt baaaaad, so you need to take them out before they take you out. There's three guys on the gate, with a Sentinel parked across the front of them. One rocket launcher later and they're dead - piece of. There's three more guys down the right hand side of the rubbish heap - so take your Colt Python or MP5 of your own (pick theirs up) and get rid of them. I tend to move down the left side of the scrapheap, where there's three more goons. On top of the crane is a Ruger-toting nut - so you'll want to get rid of him with a Sniper Rifle round. There's then three guys left guarding Lance, but you can take them from distance. You can now stop Lance's torture and get him out of there.
Firstly, make sure there's no-one left. Lance can't take many bullets, and if you've been careless, neither can you. So hang around the doorway and wait for them to come to you. With their purple Hawaiian shirts, you can't miss them. Now get Lance into a vehicle and get out of there. Your first instinct will be to get Lance into the Sentinel next to the garage, and although it's certainly possible to finish the mission with it (I have many a time), I'd skip it and make for the Trashmaster a little way off - for reason which will become more clear.
As soon as you exit the Junk Yard, four Comets of Diaz goons will come from ahead and attempt to obliterate your car. Not happening with the Trashmaster - they'll bounce right off. Now you just have to get Lance to the Downtown hospital without tipping the Trashmaster. Easy as.
Mission Reward: None. What a pisser. Cortez contact reopened (for the last time) at the Marina (after a phone call).
Go tool up first - you'll need every last bullet. Now head to the east bridge leading from Starfish Island - there'll be a pink circle there for you to go to, and it'll be given a "D" icon on the map. You'll meet Lance here. Two short cutscenes later and it's time for you to kill Diaz (at last!).
Take out as many of the Diaz goons as you can with the sniper rifle - you'll be going around the east (left) side of the mansion, so don't bother going to the middle. About halfway round the house, Lance will suddenly say "This way" and run off. Chase the idiot and protect him from (much) harm - a Colt Python would be ideal, but don't accidentally shoot him. You'll go around the back of the house and in through the indoor pool area - there are doors open here now. Head for the east entrance.
Head up the stairwell - there's four guards as you rise, so Colt Python them too. When you reach the first exit, take it, don't go to the top. Don't worry about leaving Lance behind - at least he can't get shot.
Now you're in the heart of the mansion, around the stairwell. There's four more MP5-toting goons here, so take them out. Diaz will come out of his office and confront you. Kill the fecker. One cutscene later an you're done with him. Say goodnight , Mr. Diaz.
Mission Reward: Mansion acquired; $50,000; Vercetti Mansion missions opened; Love Fist contact point opened (after phone call).
Cutscene time - Lance, Avery and Ken advise you on what to do with your new position in Vice City. Your solution? Violence... Businesses aren't paying protection now that Diaz is dead. Head up to the Northpoint Mall and smash the windows of the jewellery shop, the Tarbrush Cafe, the record shop and Gash all within five minutes, to scare them.
It's simply a case of leaping in a fast car - the Infernus that's always there is good, but there's a Stinger put for you too and getting to the mall ASAP. You're on a timer - you've only got 5 minutes to get there and successfully break all the windows indicated on your radar. Once you're there, go nuts. I find an MP5 is terribly helpful and a plan works too... I go into the south-east entrance of the mall then take out the Tarbrush (2 windows), Gash's ground floor windows (6), up Gash's escalator and take their 1st floor windows (6), over to the record store (5), then down the middle escalators to the random other shop (2 windows) and the jewellers' (3 windows). And you're done. Now you can buy the assets all over the map...
Mission Reward: $2000; All assets buyable
A local bar won't pay their protection money. So you need to go MAKE them.
Head down to the Front Page Bar - it's on Ocean Drive. You need to get into the 4-door Sentinel provided for the purpose, so the two hired heavies you have with you can get in. They're close to useless, but hey. There's two guards on the door, so drive-by them. Then go to the pink blip to meet the owner. He tells you that DBP Security are the ones trying to muscle in on your patch, so you need to get round there and toast them. You're given a 5 minute timer...
DBP Security is a little fenced in building a short way to the north. Head there and marvel at the host of pink arrows. One rocket launcher should do the trick. Once you're done with them, two PCJ-600s will come screaming out of the alley - get them too. You'll most likely need to chase one or both of them down, so leap back into your car. They're not going all that fast, so just run them down and mash them with the car. Piece of.
Mission Reward: $4000
Another one of the great missions. One of Lance's guys has screwed up again. Mike the Goon was supposed to blow up the Tarbrush Cafe in the Northpoint Mall, but it's not gone to plan, and you need to do something about it...
Lance's plan needs you to lure some cops into a lockup to nick their uniforms. So all you have to do is drive to the lockup, then get a wanted level to make a squad car follow you inside. Easy - and fun! Find a cop. Kill him. This will give you a two star wanted level. Now drive slowly back to the lockup - slowly enough that the police follow you, but not so slow that they catch you. Get a car to follow you into the garage, the garage door closes and when it opens it's just you and Lance, dressed as cops and your wanted level has gone.
Now grab a cop car - there's one around the back of the lockup - and drive to the south-east entrance of Northpoint Mall. Head inside - the Tarbrush Cafe is to your right. There's two soldiers guarding it. Walk into the marker to plant the bomb and then...
Mission Reward: $10000; Protection Ring Asset Complete ($6000 a day generated at Mansion); Cop outfit at police station in Washington Beach.